Filament lamp for emission of yellow light

Abstract

A filament lamp for an emission of yellow light, with a color film which is formed on the surface of the bulb, where the color film is essentially composed of a combined oxide of titanium, nickel and antimony. The color film may have a ratio of titanium, nickel and antimony to one another in a weight ratio of 5.6 to 8.6:3.6 to 6.6:1.0 to 1.8. Also, the color film may be a sintered coating formed by admixing a solution A produced by dissolving a nickel salt and an antimony salt in an organic solvent, addition of a titanium alkoxide and reaction of the reaction mixture; and addition of a stabilizer which forms a chelate with titanium with a solution B produced in substantially the same manner as solution A. The solutions A and B contain nickel nitrate-6-hydrate, antimony trioxide, tetraisopropoxy titanium, acetyl acetone, and/or water.

Description

1. Field of the InventionThe invention relates to a filament lamp for emission of yellow light. The invention relates especially to a filament lamp for emission of yellow light which is advantageously used for a head lamp or a fog lamp of a motor vehicle.2. Description of Related ArtFor example, a lamp which emits yellow light is used as the head lamp or fog lamp for a motor vehicle so that the driver acquires a suitable visual field even in thick fog or rain. In one such lamp, the standard range of chromaticity of the emitted yellow light is established by "ECE Regulation No. 37."Conventionally, as the lamp for emitting yellow light which is used for a motor vehicle head lamp a lamp is known which comprises:a filament lamp with a colorless, transparent bulb;a concave reflector which surrounds this filament lamp; anda front glass which is located in an opening of this concave reflector, and in which the front glass is colored yellow by a cadmium-based dye.However, since a heavy meta...

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Problems solved by technology

However, since a heavy metal, such as cadmium or the like, has adverse effects on the human body, with respect to the environment, it is desirable not to use a material which contains a heavy metal, such as cadmium or the like, in a lamp for a motor vehicle.

However, since a color film which is obtained by this composition does not satisfy the chromaticity range established by "ECE Regulation No. 37" or has a low light beam transmission factor, it is not suited for a color film for a lamp.

Furthermore, when a dispersion mixing device, such as a ball mill or the like, is used to distribute the vanadium pentoxide powder, there is the danger that changes in the shade of the color film occur, and a reduction in the light beam transmission factor will arise, as a result of the fact that, when producing the composition, a powder is mixed in originating from the grinding medium and the inside wall of the device which has been formed by abrasion.

Since it has the property that light is transmitted in a certain wavelength range, and at the same time, also has the property that light is reflected in a certain wavelength range, there is the disadvantage that, depending on the variation of the layer thickness and the radiation angle of the light, light besides yellow light is emitted.

Neither are the salts used especially limited.

At a thickness of the color film 20 of less than 2 microns, there are cases in which it is difficult to obtain the desired yellow light.

In the case of a percentage by weight of less than 65% a viscous coating liquid is obtained by which there are cases in which control of the layer thickness becomes difficult when this coating liquid is applied.

In the case of an overly small ratio of use of the nickel salt, the color film obtained often has too little a yellow shade and low tinctorial power.

In the case of an overly large ratio of use of nickel salt, the color film obtained often has cloudiness and low transparency.

Furthermore, cracks often arise in this color film and the heat resistance decreases.

In the case of an overly small ratio of use of the antimony salt, the color film obta

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